Finance Minister Elena Salgado also says said a government fund that has been pouring money into mergers among troubled cajas, or savings banks, might eventually buy stakes in the entities that cannot meet the new criteria.

She says that for that to happen banks will have to be listed on the stock market. The savings banks or cajas are not listed.

Worries about Spain's banking system have been an aggravating factor in the government debt crisis plaguing the eurozone.

Spain says its banks will need 20 billion euros ($27 billion) in fresh capital to meet new reserve requirements aimed at strengthening their finances.Finance Minister Elena Salgado also says said a government fund that has been pouring money into mergers among troubled...